In full view wallpaper screen, tap “Save" button in the top right corner of the screen
The wallpaper is now saved in your Camera Roll of Photos app
Open the saved wallpaper from Camera Roll
Tap the “Share” button of bottom left corner of the screen
Tap the button saying “Use as Wallpaper” at the bottom
Make sure the “Perspective Zoom: Off” only for App Shelves & App Frames
Tap Set button in the bottom right corner
Set as either lock screen or home screen or as both
Congratulations! your wallpaper is set successfully
NB: If you can't save wallpapers please follow the instruction to solve this problem - At first go to "PRIVACY" option inside "SETTINGS" in your device, then go to "PHOTO" option and turn "ON" access for this app.